On a Theorem of Burde and de Rham

We generalize a theorem of Burde and de Rham characterizing the zeros of the Alexander polynomial. Given a representation of a knot group $\pi$, we define an extension of $\pi$, the Crowell group. For any GL(n,C) representation of $\pi$, the zeros of the associated twisted Alexander polynomial correspond to representations of the Crowell group into the group of dilations of C^n.